This is the time of year when we can see plumage changes in progress,
and actually observe the process of moult, whereas at other times of year we can
only use the results. For the benefit of our readers from overseas, I should
perhaps explain that very few British ringers ever examine skull ossification,
determining age on the moult and wear of plumage, shape of tail feathers and so
on, and the coloration of bare parts for some species.

Whitethroat Sylvia communis is
one of the warbler species in which the adults undergo their full moult here,
fitting it in quickly between breeding and southward migration. After completion
of the moult, the wings of adults look very fresh and quite similar to those of
first-year birds. The shape and texture of the primary coverts is useful, but
can be difficult to apply. The montage below shows (on the left) a first-year bird just
finishing its post-juvenile moult of its median coverts, and (in the centre and
on the right) two
adults coming towards the end of their full moult, neither having any old
feathers left and both actively moulting their outermost primaries and innermost
secondaries. The difference in colour between the
two adults is mainly a trick of the light, but they both show another
interesting aspect of Whitethroats in the irregular moult of the secondaries. In
both of these birds the innermost secondary, s6, next to the tertials, is almost
fully grown and was moulted before the middle secondaries s4 and s5. Some
Whitethroats have been reported to retain some old secondaries, and this is
another feature that we should look out for.

Whitethroat is one of the passerines in which eye colour is
quite helpful in ageing. The following composite image shows (top) a first-year
bird (Euring age code 3) and (below) an adult bird (Euring age code 4). The
adult bird has a paler, more reddish-brown iris than the muddy-grey-brown iris
of the young bird. The species' white throat is often, as with these two, much
cleaner and whiter in the adult, without the grey suffusion of the first-year
bird. The adult bird is almost certainly a female, males usually being much
greyer on the crown.

The tail shape and coloration can also be
particularly helpful in ageing Whitethroats, provided that the usual care is
taken not to be misled by first-year birds that have moulted some or all of
their tail. First-year Whitethroats seem especially prone to growing new
outermost tail feathers. Incorrect ageing can of course be avoided by not using
any one character in isolation. The montage below shows three tails,
photographed 15 or 19 August in Cheshire, from (left) a typical first-year bird,
(centre) a first-year bird with an unusual amount of white in t5 and t6 (the
outermost two feathers on both sides), and (right) an adult bird towards the end
of its full moult (t4, t5 and t6 had not quite finished growing, and t4 on its
left side - the right side of the photo - is hidden). Again, the colour balance is
affected by the sunlight and the colours are not wholly accurate, but the
generally more grey tone of the adult is correct, and especially the amount and
extent of the pure white on the outer rectrices is the key feature. These pages
have illustrated some of these points before.

Great Spotted Woodpecker
Dendrocopos major juvenile birds have a red crown (the
top of the head), not to be confused with the red nape (back of the neck) that
male birds have:

The iris is brown, and becomes red with age, as shown
previously in these pages. Juvenile birds undergo a
full moult of all of their primary feathers, but not the corresponding
primary coverts:

Juvenile primary feathers have an off-white spot at the tip
which is absent in the 'adult' type primary feathers grown in the
post-juvenile moult, but this feature is not particularly helpful in ageing, as all
birds with 'white-tipped' primaries also have at least some of the red crown
feathers, which is a pretty obvious give-away for a juvenile bird.

Adult birds moult primaries as well, of course, but they
also moult secondaries, tertials, tail and indeed most of their feathers (but
not usually all of them, as the moult of older woodpeckers is complex). The
possible confusion in ageing comes later in the year when the juveniles have
finished their post-juvenile moult, lost all the red on the crown, and finished
moulting their primaries. As shown in the picture at the left, moult of
the primary feathers without the corresponding primary
coverts is a characteristic feature by which woodpeckers can be aged at
other times of year. The same also applies to the North American species such as
Downy Picoides pubescens and Hairy Picoides villosus Woodpeckers,
and Northern Flickers Colaptes auratus.

These pages have previously carried extensive articles on
moult in first-year finches, including GreenfinchesCarduelis chloris where about
one-in-ten birds in winter 2003/ 04 had moulted one or more primary feathers.
Now is the time of year when the first-year birds are actively moulting and is
the ideal time to see the progress of any eccentric moult. I ring few
Greenfinches outside the winter period, but have recently caught 53 birds from a
flock of Goldfinches Carduelis carduelis, nine adults and 44 juveniles,
in which one juvenile bird was moulting four primary
feathers, pp3, 4, 5 and 6 (counting from the inside, as is usual in moult
studies). Primaries 3 and 4 were fully grown, recently moulted, and primaries 5 and 6
were still growing on 19 August:

This was an unusual bird in another way because it had a
somewhat deformed bill, curving downwards and with an extended lower mandible
(left photo below), contrasting with the normal juvenile at the right:

A young Linnet Carduelis cannabina accompanying the
Goldfinch flock also had feathers still growing, but in this case it was because
it was so recently fledged that it was still not fully grown: a 1J in Euring
code, known as 'Local' to North American banders. Even at this age, many birds
are sexable on the basis of the amount of white on the primaries; this bird has
white almost to the feather-vane and is a male. The photograph of the underwing
shows the growing feathers still emerging from their pins, and the underwing
coverts just starting to grow: